Morphometric analysis of postnatal lung development in the gray short-tailed opossum (Monodelphis domestica): an ultrastructural study - Data

An ultrastructural morphometric study of the postnatally developing lung of the gray short-tailed opossum (Monodelphis domestica) was carried out to assess the morphofunctional status in this immature born marsupial. Allometric scaling of the volumes of the parenchymal components against body mass was performed. In the parenchymal septa, volume proportions of pulmonary capillaries and solid septal tissue components (type I and type II epithelial cells, capillary endothelium and interstitium) as well as alveolar and capillary surface densities were determined in transmission electron microscopic images using morphometry. Most parameters showed a positive correlation with body mass over postnatal development. The lung of the neonate was at the late canalicular stage and consisted of large terminal airspaces, which were separated by thick septa with a massive interstitial layer. A mature surfactant system is present at birth. The volume density of type II epithelial cells, which contain surfactant producing lamellar bodies, is highest in the late saccular stage, when septal growth is accelerated. The rapid development of the lung was indicated by an increase in the septal proportion of the parenchyma around day 4 and attainment of the saccular stage between day 4 and 7. The saccular stage, indicated by formation of a double capillary system, was characterized by repetitive steps of septation, increasing the number of saccular generations. By day 28 alveolarization starts and the process of microvascular maturation begins. The reduction of the interstitial tissue causes the two capillary beds to converge, finally the two capillary layers begin to fuse, leading to a single capillary septum. In adults, capillaries and alveolar epithelia are the predominant septal components, the interstitium is greatly reduced. Despite the immaturity of the gray short-tailed opossum lung, it appears to be structurally and quantitatively sufficient for gas exchange. The structural transformation of the septa is accompanied with an increase in gas exchange surface area and thinning of the diffusion barrier, in order to meet the metabolic requirements of the developing young. - This dataset contains the original data for the individual animals.